Surgical devices assembled using heat bonable materials

ABSTRACT

Surgical devices such as implants or suture fastenings are assembled from a plurality of discrete components, one of which components includes a heat bondable plastic material for bonding the components together. At least two components are bonded to each other by the applying heat to the heat bondable plastic material of one component. The heat bondable plastic material is preferably a polymeric or composite material suitable for surgical applications and implantation in humans, and may be a biodegradable material. A laser may be used as the heat source. The present invention is advantageously embodied in heat bonded fastenings for sutures or K-wires, in which a variety of different suture anchors are usable, including expandable distal suture anchors. Other embodiments include a metal bone plate which is held to bone by a metal bone screw and a nut of bondable material bonded to the plate to secure the connection; a piece of bondable material bonded to a metal prosthesis to custom fit the prosthesis; and a surgical implant custom formed by bonding together a plurality of discrete elements one or more of which is bondable.

RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.07/833,085, filed Feb. 10, 1992, now abandoned. The aforementionedapplication Ser. No. 07/833,085 is itself a divisional of 07/545,919,filed Jun. 28, 1990, and now U.S. Pat. No. 5,163,960. The benefit of theearlier filing dates of the aforementioned applications is herebyclaimed.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to surgical devices such as implants orsuture fastenings.

2. Description of the Prior Art

Mundell U.S. Pat. No. 4,506,681 shows the use of a prosthesis whichincludes a biodegradable thermoplastic material molded around electricresistance elements to allow for heating to soften to mold to aparticular shape.

Polonsky U.S. Pat. No. 4,662,068 discloses cutting off most of theprotruding ends of a plastic suture and heating them to secure the endstogether.

Jacobs U.S. Pat. No. 4,750,492 shows crimping or clipping abiodegradable fastener or retainer on the end of a biodegradable suture.

The compound methyl methacrylate is an acrylic resin monomer which issometimes used in surgery to fasten or grout implants of metal to bone,or hip or knee replacements to bone. It is usable only for bone to metalapplications. Tissue reacts to it and in soft tissue it creates afibrous scar. Further, it is not biodegradable.

SUMMARY OF THE INVENTION

The present invention includes an assembly for use in surgicalapplications in humans. The assembly may include two components, atleast one of which comprises a heat bondable material. The first andsecond components are bond to each other by the application of heat tothe heat bondable material, to make the heat bondable material soften,become tacky, and bond to the other component.

If only one of the components comprises a heat bondable material, theapplication of heat to the heat bondable material of that componentcauses the heat bondable material to soften and bond to the othercomponent.

If both of the components comprise a heat bondable material, theapplication of heat to the heat bondable material of the componentscauses the heat bondable material of at least one and preferably eachcomponent to soften and bond to the other component.

The assembly can also include a first component, a second component, anda third component separate from the first and second components andcomprising a heat bondable material. The application of heat to the heatbondable material of the third component causes the heat bondablematerial to soften and bond to the first and second components tointerconnect the first and second components.

The heat bondable material is preferably a polymeric or compositematerial suitable for surgical applications and implantations in humans,and may be a biodegradable material where such is called for by theapplication.

The present invention may advantageously be embodied in heat bondedfastenings for sutures or K-wires, in which a variety of differentsuture anchors are usable, including expandable distal suture anchors.Such suture fastenings are easier to form and stronger than conventionaltied knots. Other examples of assemblies embodying the present inventionmay include a metal bone plate which is held to bone by a metal bonescrew and a nut of bondable material bonded to the plate to secure theconnection; a wedge of bondable material bonded to a metal prosthesis tocustom fit the prosthesis; and a surgical implant custom formed bybonding together a plurality of discrete elements one or more of whichis bondable. Such embodiments are further described below.

The present invention may also provide a method of suturing body tissue.A portion of a suture is inserted into an opening in a retainer formedof a plastic material. At least a portion of the retainer is heated to atemperature in a transition temperature range of the plastic materialforming the retainer. The suture is maintained at a temperature belowthe transition temperature range of a plastic material forming thesuture while the retainer is heated. The plastic material of theretainer flows around the plastic material of the suture. A bonding ofthe plastic material of the retainer to the plastic material of thesuture is effected by cooling the plastic material of the retainer to atemperature below its transition temperature range. The foregoing stepsare performed without significant deformation of the plastic material ofthe suture.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the present invention will become apparent to thoseskilled in the art to which the present invention relates from readingthe following specification with reference to the accompanying drawings,in which:

FIG. 1 is an illustration of a metal bone plate which is held to bone bya metal bone screw and a nut of bondable material bonded to the plate tosecure the connection in accordance with one of the features of thepresent invention;

FIG. 1A is an illustration of a bone plate of bondable material which isheld to bone by a bone screw and nut both of bondable material andbonded to each other to secure the connection;

FIG. 2 illustrates the use of a bonded fastening in accordance with oneof the features of the present invention to obtain increased holdingpower on a fastener extending through a bone;

FIG. 3 is an illustration of a wedge of bondable material bonded to ametal hip prosthesis to custom fit the prosthesis;

FIGS. 4A and 4B are illustrations of a wedge of bondable material bondedto a metal tibial prosthesis to custom fit the prosthesis;

FIG. 5 is an illustration of a surgical implant custom formed by bondingtogether a plurality of discrete bondable elements;

FIG. 6 is an illustration of the use of a third component of bondablematerial to custom form a surgical implant by bonding together aplurality of discrete elements;

FIGS. 7A, 7B and 7C are illustrations of a bonded suture fastening inaccordance with one of the features of the present invention;

FIGS. 8A-8I are schematic illustrations of a variety of different sutureanchors usable in bonded suture fastenings;

FIGS. 9A, 9B, 9C and 9D are illustrations of an expandable distal sutureanchor usable in bonded suture fastenings;

FIG. 10 illustrates the use of a curved hole in tissue parts to bejoined with bonded fastenings on either end of the joining element;

FIGS. 11A, 11B and 11C are illustrations of a bonded rivet in accordancewith one of the features of the present invention;

FIG. 12 is a schematic sectional view illustrating the manner in which asuture is placed relative to body tissue and extends into openings in aretainer;

FIG. 13 is a plan view, taken generally along the line 13--13 of FIG.12, further illustrating the construction of the retainer;

FIG. 14 is an enlarged fragmentary sectional view of a portion of FIG.13;

FIG. 15 is an enlarged fragmentary sectional view, generally similar toFIG. 14, illustrating the manner in which the retainer is bonded to thesuture without significant deformation of the suture;

FIG. 16 is a fragmentary sectional view generally similar to FIG. 15,illustrating the manner in which the retainer is bonded to a braidedsuture;

FIG. 17 is a schematic illustration, generally similar to FIG. 12,schematically illustrating the orientation of polymer chains relative tothe retainer; and

FIG. 18 is a fragmentary sectional view, generally similar to FIG. 12,illustrating a second embodiment of the retainer.

DESCRIPTION OF PREFERRED EMBODIMENTS

In this application, the term "bondable" or "bondable material" is usedto refer to any material, suitable for use in surgical applications,which can be softened and made flowable by the application of heat, andwhich, when softened, will become tacky and bond to other materials andwill flow to fill available space. Thus, the material may bethermoplastic, but it may also exhibit tackiness or bonding ability whenin its plastic form. Many materials suitable for surgery are made of orincorporate such heat bondable materials. Many biodegradables, polymerssuch as polyethylene, and composites fall in this class. They can bejoined by heat bonding at reasonably low temperatures which can beapplied in the operating room safely, unlike the very high temperaturesneeded to melt metal. Composite materials can include reinforcedplastics, or polymers which are laminated or layered or reinforced withone or more other materials such as nylon, graphite fibers, Kevlar®fibers, stainless steel fibers, etc. Many sutures are made of polymerswhich are suitable for use herein. Selection of such material is withinthe ordinary skill of the art.

Various components of at least some embodiments of the invention areformed of a plastic material. A plastic material is a material whichcontains one or more polymers and which may also contain other materialssuch as fillers, solvents, plasticizers, lubricants, accelerators, dyes,etc. An interconnection or bond between plastic materials occurs as aresult of molecular attraction (adhesion) and/or mechanical forceresulting from shrinking of the plastic material. A transitiontemperature range of the plastic material is a temperature range atwhich the plastic material changes from a solid condition in which ithas a fixed form to a viscous condition in which the material readilyflows and is soft enough to be molded.

Any suitable heat generating apparatus can be used to heat and soften orspot weld the material, such as a hot air gun, a small welding orsoldering gun, or a Bovie tip. Also usable are lasers, which arecommonly provided in operating rooms. Lasers are especially desirablebecause they are precise and controlled in their application, cangenerate sufficient heat very quickly, and cause less thermal necrosisbecause there is less misdirected heat. The heating operation can bedone pre-operatively to form an assembly; can be done outside the bodybut in the operating room to customize implants at the time of surgery;or can be done during surgery, in the body, when the bond is neededwithin the human body.

First Embodiment

FIGS. 1 and 2 illustrate heat bonded assemblies including existingsurgical objects such as plates, screws, etc. In FIG. 1, a bone plate 10is secured to bone material 12 by a bone screw 14. The bone plate 10 andthe bone screw 14 are both made of metal. Ordinarily, the bone screw 14would be secured to the bone plate 10 by a metal nut threaded onto thebone screw 14 and run up adjacent the bone plate 10. However, such aconnection can loosen and thus destroy the integrity of the assembly.Accordingly, in accordance with the present invention, a nut 16 isprovided which is made of or includes a bondable material. The nut 16 isthreaded on the bone screw 14 into abutting engagement with the boneplate 10. Then, the bondable material of the nut 16 is heated andsoftened to flow about the joint between the nut 16 and the bone plate10, to bond the nut 16 to the bone plate 10. The nut 16 can also be bondto the bone screw 14 if desired for a stronger connection.

FIG. 1A illustrates an assembly similar to FIG. 1 in which a bone plate18 and a bone screw 20 both made of or including bondable material areprovided. The nut 16 (FIG. 1) is not used. Instead, the bone screw 20 isbonded directly to the bone plate 18 at an area 22.

As noted, ordinarily a bone plate is held to bone via a threadedfastener such as the bone screw 14 or 20 in FIG. 1. However, the bone isalive and is constantly remodeling the threads on the bone screw. Asthis happens, the fastener loses its purchase or holding power in thebone, and the screw can pull loose. Accordingly, it would be desirableto obtain more purchase by a different kind of fastener.

FIG. 2 illustrates the use of a bonded fastening in accordance with thepresent invention to obtain increased holding power. The fastenerextends completely through a tissue mass such as a bone 160, for exampleto secure a plate in position against the bone. An elongate fastener162, which may be metal or may be made of or include a bondablematerial, is inserted through an opening in the bone 160. A distalfastener 164 is secured to the distal end of the screw 162 by a plug ofbonded material 166. The plate 168 is then placed over the bone screw,and a proximal fastener 170 made of or including a bondable material isbonded to either or both of the screw 162 and the plate 168. Theelongate fastener 162 may optionally also be threaded in the portionengaging the bone 160. The elongate fastener 162 may optionally also bethreaded in the portion engaging the fastener 164 and/or the fastener170.

The bonded fastenings obtained thereby are stronger than is possiblewith either a threaded connection or a tied or crimped connection.Further, there is no reliance on a threaded connection between bone andfastener which will inevitably weaken over time. Also, bone screws arethreaded and are always straight. The elongate fastener 162 need not bestraight because it need not be threaded. Thus, it can be curved, orangled, as needed or desired to fit any particular application. Incombination with the bonded connection of the fasteners at the ends ofthe elongate fastener, such a structure is a vast improvement over atypical metal threaded fastener.

FIGS. 3 and 4 illustrate surgical assemblies in which an existingsurgical prosthesis or implant has been modified to better fit theparticular application. Such prostheses or implants come from amanufacturer in only a limited range of sizes and shapes. However, theparticular bone into which a prosthesis or implant is to be inserted mayhave defects or size discrepancies which would make it impossible toobtain a good fit with even the closest fitting prosthesis or implant.

In accordance with one of the features of the invention, the shape andsize of a prosthesis or implant are modified to fit a particular bone. Afemoral prosthesis 30 illustrated in FIG. 3 has been modified with theaddition of a wedge 32 including heat bondable material in order tobetter fit a gap 34 in the bone 36. The wedge 32 is custom shaped to fitthe gap 34 exactly. The connection 38 between the wedge 32 and theprosthesis 30 is secured by heating and softening the wedge 32 so thatthe material of the wedge 32 adheres or bonds to the prosthesis 30. Theassembly of the heat bondable wedge 32 and the femoral prosthesis 30fits the femur 36 much more properly than would the prosthesis alone.This assembly can easily be made right in the operating room at the timeof the joint reduction, allowing the surgeon to customize or equilibrateat the time of surgery.

Similarly, in FIG. 4, a tibia 40 is shown to have an area of defect 42which makes it impossible to properly fit a tibial component 44.Accordingly, as seen in FIG. 4B, an element 46 including a heat bondablematerial is shaped with heat as by a laser in the operating room to fitthe defect 42. The element 46 is then bonded to the tibial component 44prior to placement thereof in the bone 40. The assembly of the tibialcomponent 40 and the element 46 provides a proper fit in the tibia 40.There is no other suitable way of matching the requirements of bone andjoint in the operating room.

The bone components shown in FIGS. 3 and 4 are only an illustration ofthe many kinds of objects which can be used to form assemblies embodyingthe present invention. It can thus be seen, as illustrated in FIGS. 3and 4, that the present invention gives the surgeon the ability toimmediately modify the shape and size of almost any existing surgicalpart including a prosthesis, in order to better fit the particularapplication for use in the body. This is accomplished by heat bonding apiece of bondable material onto the prosthesis, to make an assemblydesigned for the particular application. The piece can be custom shapedin the operating room to fit the application exactly by heating andbonding of a polymer or composite.

FIGS. 5 and 6 illustrate schematically some custom fabricated implantswhich can be constructed in accordance with the present invention. InFIG. 5, a relatively thick plate 50 is joined to a relatively thin plate52. Both the plate 50 and the plate 52 are made of or include a bondablematerial. The plates 50 and 52 are joined at the area of the joint 54between them, by bonding in accordance with the present invention. Athird element such as a stud 56 may be added, with bonding at the joint58 therebetween. Thus, the surgeon has the ability to laminate pieces insurgery and does not have to rely on pre-made hardware.

It should be understood that the illustration in FIG. 5 of plates and astud is not limiting, but is only illustrative of the almost limitlessnumber of surgical devices which can be constructed in accordance withthe present invention. Items such as rods, bars, plates, or any type ofconstruct usable in medical/surgical applications object can be customshaped or built up in accordance with the present invention. They can bemade of polymers or composites which can easily be cut with a laser andalso softened to custom fit. They can be made of or include abiodegradable material in those instances where it is desired that thematerial be replaced, over time, with natural tissue ingrowth. They canalso include tissue ingrowth promoters, antibiotics, or other additivesas desired.

Rather than having one or both of the components to be joined made of abondable material, a third component can be used to join them, with thethird component being made of or including a heat bondable material. Thethird component is non-flowable and non-adherent at room temperaturebefore use. When it is softened by heating and applied to the first andsecond components, it bonds to both components to interconnect them. Alaser is ideal for heating the interpositional bonding material becauseof the accuracy available with the laser. As an example, FIG. 6illustrates an assembly similar to FIG. 5 in which a plate 60 and aplate 62 and a stud 64 are joined by the use of additional bondingmaterial at locations 66, 68, 70, and 72. In this case, the plates 60and 62 and the stud 64 need not be made of heat bondable materials.

For example, a total hip or knee replacement is possible usingcomponents bonded together by heat. If some or all of the parts are madeof heat bondable material such as polymers or composites, an assembly asdescribed herein can be produced simply by the application of heat tobond the parts together as desired. If the replacement does not fit theexisting bone exactly, it can be customized at the time of surgery bycutting as with a laser, by adding as by bonding, or by heating to bondwedges or pieces to it.

It can be seen that the present invention also provides the capabilityfor forming a custom-fit surgical implant for bonding to a bone or to abone prosthesis which comprises a component at least partially formed ofa heat-bondable material which has been custom-shaped by the applicationof heat to said heat-bondable material. In this instance, theaforementioned laser is most suitable for forming the implant. Thelasers which are commonly found in operating rooms can cut, shape, andotherwise form almost any suitable material used herein, includingpolymers, biodegradable materials, and even composites includingreinforcing materials. The implant can include several components eachhaving heat-bondable material, or several components only one of whichincludes a heat-bondable material, or it can be a single component whichis custom made for a particular application. Such use of heat to formimplants provides the surgeon with greatly extended capabilities in theoperating room and does not limit him to pre-formed implants orprostheses.

Second Embodiment

It is difficult to tie a suture knot to itself or to slide it downthrough deep tissue in a limited working area (as in fiber opticsurgery). Typically, the surgeon can often not work in a straight linebut needs to use a suture loop (going through the tissue twice) to bringtissue together. Any such increase in the amount of tissue through whichthe suture must pass increases damage to tissue. Furthermore, mechanicaltying or crimping of sutures or K-wires, especially of polymers orbiodegradables which are generally smooth, does not produce connectionswhich are as strong as desirable, and suture connections sometimes maycome untied as a result.

In accordance with one of the features of the present invention,surgical connections for holding adjoining tissues together are securedby melting a fastener or anchor on the end of a suture, rather than bytying or by clipping the anchor on the end of the suture. (The term"suture" is used herein to refer to a suture, a K-wire, or any similarsurgical connector.) The anchor is pushed over the free end of thesuture down to the tissue, drawing the tissues together. Either theanchor alone or the anchor and the suture are melted together to lockthem into position.

With the fasteners of the present invention, therefore, a surgeon hasmore control since he can apply more pressure to push the tissuestogether and it is easier to appose the tissues; the tension on therepaired tissues is more controllable, predictable, and reproducible;and the fasteners can be used in a smaller working space. Further, amelted anchor provides a stronger bond than the mechanical interlock ofa suture knot, because it will not unravel or come apart as a surgicalknot may. It takes less time to fasten than it does to tie a suitableknot. There is improved contact between the tissues being joined becauseof the better suture connection. The straight line suture fastening alsoavoids buckling of the tissue edges caused by force vectors notextending in the direction of the suture.

Since he only needs one free suture end to make a secure connection, thesurgeon does not need to use a suture loop to bring tissue together, butcan work in a straight line. This lessens damage to tissue because astraight line connection is easier to obtain than a loop in a limitedspace. Also, it improves tissue apposition and approximation when astraight line fastening is pulled together rather than a loop whichtends to buckle or pucker tissue at the edges because of the forcevectors not directed along the length of the suture.

The fasteners can be used for the fixation of soft tissue, tendon,ligament, meniscus, muscle, fascia, vessels, nerves or bones to eachother. They can be used, for example, to hold a rotator cuff to bone, orto join fracture fragments of bone to bone. The anchors can be custommolded, specially made at the time of surgery (or preoperatively) toconform exactly to the tissue or bone application.

One anchor is secured to the distal end of the suture. (Alternatively,it may be preformed or connected on the suture in any known manner ofconnection.) The suture is then positioned in the tissues to be joined,a second anchor is slid over the free end, pulled down to close the gap,and melt it in place.

As illustrated in FIG. 7, two pieces of tissue 80 and 82 are to bejoined using a suture 84. A distal anchor 86 is located on the end ofthe suture 84. The suture is then inserted through the tissues 82 and 80so that a free end 88 of the suture 84 protrudes at the proximal end. Afastener 90 having an opening 92 therein is slid over the wire 84 andpulled down tight as shown in FIG. 7C to close the gap 94 between thetissues 80 and 82.

The fastener 90 is made of a heat bondable plastic material. (The suturecan also be made of heat bondable plastic material which is bonded tosecure the connection.) The fastener 90 is then bonded at an area 96 tothe protruding free end 88 of the suture 84. In FIG. 7C, it can be seenthat the fastener 90 is bonded to the suture 84 without significantdeformation of the suture. Alternatively, the fastener 90 can be bondedalong the length of the opening 92 to the suture 84. The protruding endof the suture 84 is then cut off. Applicant has found through testingthat while a simple mechanical connection such as a knot or a crimpedconnector is not strong enough to hold in some circumstances, the bondedconnection illustrated in FIG. 7 overcomes this difficulty and willhold.

FIG. 8 illustrates a few of the many fasteners which can be used inaccordance with the present invention. FIG. 8A shows a simple squarefastener 100 having a suture receiving opening 102 therein. The fastener104 is round and has an opening 106 therein. The fastener 108 shown inFIG. 8C includes a plurality of barbs 110 for better gripping in thetissue against which it engages. The fastener 112 shown in FIG. 8 isumbrella-like in shape, having an outer rib 114 and a plurality ofradially extending ribs 116.

The fastener 118 shown in FIG. 8E is filamentous, having a plurality ofprotruding filaments 120. The fastener 122 shown in FIG. 8F is a T-snap.The fastener 124 shown in FIG. 8G is curved or cupped about the opening126 so that its ends 128 and 130 will flatten as pressure is appliedupon drawing tight the suture. The fastener 132 shown in FIGS. 8H and 8Iis reinforced with transverse ribs 134 and longitudinal ribs 136 forbetter strength. The ribs 134 and 136 protrude axially from the mainbody 138 of the fastener. Finally, any anchor or fastener can bespecially made, that is, custom molded at the time of the surgery orpreoperatively to conform exactly to the tissue against which it will beabutting.

FIG. 9 illustrates the use of an expandable distal suture anchor forbonded suture fastenings in accordance with the present invention. Inparticular, FIG. 9 illustrates the use of a bonded assembly to secure atendon 140 to bone 142. To make the assembly, initially, a cannula orsleeve 144 is inserted through the tendon to the bone. A gouge 146 isthen used to gouge out an opening 148 in the soft cancellous tissueunder the cortical bone. An expandable anchor 150, confined in a sleeve152 and having a suture 154 extending proximally from the sleeve 152, isinserted through the canula 144 into the opening 148 in the bone. Thesleeve 152 is then withdrawn, allowing the anchor 150 to expand withinthe opening 148, blocking removal of the suture.

A fastener 156 made of or including a bondable plastic material is thenslid distally over the suture 154 into engagement with the tendon 140,and then further, pushing the tendon 140 into engagement with the bone142. The anchor 156 is then bonded to the suture 154, providing aconnection which is stronger than that of any tied knot. In FIG. 9D, itcan be seen that the fastener 156 is bonded to the suture 154 withoutsignificant deformation of the suture. In a similar manner, anexpandable anchor as illustrated herein can be used with a bondedfastening in any application in which the anchor must be placed in ablind location. This method can work also especially well with a barbedor umbrella-like anchor as illustrated in FIGS. 8C or 8D.

FIG. 10 illustrates the use of bonded fastenings in accordance with thepresent invention in conjunction with a curved opening in tissue partsto be joined. Illustrated in FIG. 10 are two portions 172 and 174 of afractured bone with their ends abutting at a joint 176. It is possibleto secure together the bone ends with a suture which extends axiallythrough the fractured ends of the bone, while accessing the joint onlyfrom one side of the bone. A curved opening 178 is drilled through thefirst bone part 172 and the second bone part 174, beginning at theproximal end of the first bone part 172, extending through the joint176, and exiting at the proximal face of the second bone part 174. Asuture 180 is then passed through the opening 178. A first fastener 182made of or including a bondable plastic material is then bonded onto theprotruding end of the suture 180. The suture is then pulled tight, and asecond fastener 184 also made of or including a bondable material ispulled down tight against the proximal face of the second bone part 174and bonded by heating in location to the suture 180. In FIG. 10, it canbe seen that the fasteners 182 and 184 are bonded to the suture 180without significant deformation of the suture.

FIG. 11 illustrates the use of a bonded fastening in accordance with afeature of the present invention in conjunction with a rivet typefastening. To secure together two adjoining masses 186 and 188, a sleeve190 is inserted through an opening in the tissues until the distal end192 of the sleeve projects behind the tissue 186. A mandrel 194 in thesleeve 190 has a headed portion 196 at its distal end 192. The mandrel194 is then pulled outwardly, while the sleeve 190 is held in place,spreading the distal end 192 of the sleeve to lock the sleeve in placebehind tissue 186. The protruding end of the mandrel 194 is then cut offflush with and bonded by heating as at 198 to the head end 200 of thesleeve. This type of bonded connection can be used in variousapplications where the surgeon is connecting two tissue masses withaccess only from one side thereof.

The present invention also is embodied in a method of making an assemblyfor use in surgical applications in humans. The method comprises thesteps of providing a first component which comprises a heat bondableplastic material; providing a second component; and bonding the firstand second components to each other by the application of heat to theheat bondable material to make the heat bondable material bond to theother component. In the method, the second component may be a surgicalprosthesis or implant, or it may be a bone plate or bone screw. The heatbondable plastic material used in the method may be a polymer, acomposite, or a biodegradable material.

The present invention also is embodied in a method of fastening a sutureor K-wire to hold together adjoining tissue masses in a human surgicalapplication. The method comprises the steps of inserting the suture intothe desired location in the tissue masses, placing in position on thesuture a suture fastener, and bonding the suture to the fastener byapplying heat to one or both of the fastener and the suture to bond thefastener to the suture. Further, the fastener may be mechanicallycrimped first and then heat bonded to provide the benefits of both typesof fastenings.

The present invention is also embodied in a kit of components forforming an assembly by heat bonding for use in surgical applications inhumans and incorporating at least one heat bondable material. The kitcomprises a first component and a second component comprising a heatbondable material, with the first and second components bondable to eachother upon the application of heat to the second component to make theheat bondable material of the second component bond to the firstcomponent. The kit may further include heat generating means forgenerating heat to bond said first component to said second component.The components and the heat generating means are as described above withrespect to the assemblies.

Method and apparatus for Suturing Body Tissue

An apparatus 220 for use in suturing human body tissue (FIG. 12)includes a retainer or crimp 222 and a suture 224. The suture 224extends through a layer 226 of skin into body tissue 228 disposedbeneath the skin. Although the suture 224 as been illustrated in FIG. 12in association with soft body tissue 226 and 228, it is contemplatedthat the suture 224 could be used in association with relatively hardbody tissue, such as bone. The suture 224 may be placed in manydifferent locations in the human body for many different purposes. Forexample, the suture 224 may be used with a suture anchor in the mannerdisclosed in U.S. Pat. No. 5,403,348, issued Apr. 4, 1995 and entitledSuture Anchor.

The retainer 222 is formed of a plastic material. The suture 224 is alsoformed of a plastic material. The retainer 222 is bonded to the suture224 without significant deformation of the suture. This enables theretainer 222 to securely hold the suture relative to the body tissue 226and 228 without impairing the strength of the suture. Although theretainer 222 has been shown in FIG. 12 as being connected with oppositeend portions of a single suture 224, the retainer could be connectedwith end portions of two separate sutures.

In the illustrated embodiment of the invention, the retainer 222 has agenerally cylindrical configuration (FIGS. 12 and 13). The retainer 222has a pair of linear cylindrical passages 232 and 234 through which thesuture 224 extends. Thus, a portion 238 of the suture 224 extendsthrough the passage or opening 232. A portion 240 of the suture extendsthrough the passage or opening 234 (FIG. 12).

In the suture arrangement illustrated in FIG. 12, a connector portion242 of the suture 224 interconnects the two portions 238 and 240. Ifdesired, the connector portion 242 of the suture 224 could extendthrough a suture anchor. It is contemplated that the connector portion242 of the suture 224 could extend around ligaments or other human bodytissue. It is contemplated that the retainer 222 could be used tointerconnect sutures in a series of sutures.

After the two portions 238 and 240 of the suture 224 have been insertedinto the passages or opening 232 and 34 in the retainer 222, theretainer and suture are interconnected to hold the suture againstmovement relative to the body tissue. To interconnect the retainer andthe portion 238 of the suture 224, the plastic material of the retainer222 is heated to a temperature in a transition temperature range of theplastic material of the retainer 222. The plastic material of the suture224 is maintained at a temperature below the transition temperaturerange of the plastic material forming the suture.

Thus, in the specific embodiment of the invention illustrated in FIGS.12-15, the plastic material of the suture 224 has a transitiontemperature range which is above 190° Celsius. The specific retainer 222illustrated in FIGS. 12-15 has a transition temperature range which isbelow 190° Celsius. However, it should be understood that at least aportion of or even the entire transition temperature range for thesuture 224 could be coextensive with the transition temperature rangefor the retainer 222. In fact, the transition temperature range of thesuture could extend below the transition temperature range of theretainer. However, it is believed that it will be advantageous to have ahigher transition temperature range for the suture than for theretainer.

Once the plastic material of the retainer 222 has been heated to atemperature in the transition temperature range for the plastic materialof the retainer, the plastic material of the retainer flows around theplastic material of the suture 224. This occurs while the plasticmaterial of the suture 224 is maintained at a temperature below thetransition temperature range of the plastic material of the suture.Thus, the portion of the plastic material of the retainer 222 formingthe passage 232 (FIG. 14) is heated to a temperature in its transitiontemperature range. The plastic material of the retainer 222 then flowsinwardly around the portion 238 of the suture 224 to eliminate thepassage 232 (FIG. 15).

As this occurs, the portion 238 of the suture 224 maintains its originalconfiguration and is not significantly deformed. Thus, an outer sidesurface 242 of the suture 224 has the same cylindrical configurationalong the length of the suture both in the areas where the outer sidesurface of the suture is exposed to the heated material of the retainer224 and in the areas where the suture is not exposed to the heatedmaterial of the retainer 222. By maintaining the configuration of theportion 238 of the suture exposed to the heated material of the retainer222 constant, the suture 224 is not weakened in the areas where it isexposed to the heated material of the retainer.

After the material of the retainer 222 has been heated and flows aroundthe portions 238 and 240 of the suture 224, in the manner illustratedschematically for the portion 238 of the suture in FIG. 15, the heatedplastic material of the retainer is cooled to a temperature below thetransition temperature range of the plastic material of the retainer. Asthe plastic material of the retainer is cooled to a temperature belowits transition temperature range, the plastic material of the retainerbonds to the suture 224. Thus, the plastic material of the retainer 222bonds to the portion 238 of the suture 224 and bonds to the portion 240of the suture.

As the plastic material of the retainer 222 is cooled and bonds to theouter side surface 242 of the suture 224, a secure interconnectionoccurs between the material of the retainer 222 and the material of thesuture 224 at the portions 238 and 240 of the suture. Theinterconnection between the material of the retainer 222 and thematerial of the portion 238 and 240 of the suture is the result of bothmolecular attraction (adhesion) of the material of the retainer 222 tothe material of the suture 224 and due to a mechanical interconnectionbetween the material of the retainer 222 and the material of the suture224. Thus, as the material of the retainer 222 cools, it mechanicallygrips the suture 224 so that the suture is held against movementrelative to the retainer by interfacial forces between the material ofthe retainer and the material of the suture. Thus, there is a fusing ofthe material of the retainer 222 to the material of the suture 224 alongthe portions 238 and 240 of the suture.

The suture 224 is formed of a plastic material which may be abiopolymer. In one specific embodiment of the invention, the suture isformed of polyglycolide (P-G) (C₄ H₄ O₄) which is commercially availableunder the trademark Dexon. Polyglycolide is a crystalline material(40-55% crystallinity) that melts at about 225° Celsius. Although thesuture 224 is a monofilament suture having a continuous cylindricalouter side surface 242, it is contemplated that this suture could beformed in a different manner. For example, the suture could be a braidedsuture.

It is also contemplated that the suture 224 may be formed of a highglycolide-based copolymer, specifically a 10/90 P-LL/G (10% polyl-lactide and 90% glycolide) which is commercially available under thetrademark "Vicryl". "Vicryl" is a crystalline material that melts atabout 205° Celsius. "Vicryl" can be used for either a monofilament orbraided suture.

The retainer 222 is also a plastic material which may be a biopolymer.In one specific embodiment of the invention, the retainer 222 is formedof poly dl lactide (P-DLL) (C₆ H₈ O₄) and is amorphous and has aprocessing temperature of approximately 120° Celsius. The transitiontemperature range of poly dl lactide will vary depending upon thespecific characteristics of the material. However, the retainer 222 ofFIGS. 12-15 had a transition temperature range of from about 75° Celsiusto about 120° Celsius.

In another specific embodiment of the invention, the retainer 222 isformed of poly dl lactide (P-DLL) (C₆ H₈ O₄) and poly l lactide (P-LL)(C₆ H₈ O₄) copolymer and is a material having a melt temperature ofapproximately 165° Celsius. The transition temperature range of the polydl lactide and poly l lactide copolymer will vary depending upon thespecific characteristics of the copolymer and is from about 75° Celsiusto about 180° Celsius. In still another specific embodiment of theinvention, the retainer 222 is formed of poly l lactide (P-LL) and has amelt temperature of approximately 145°-185° Celsius. A transitiontemperature range of poly l lactide is from about 70° Celsius to about185° Celsius.

It is contemplated that the retainer 222 may be formed of many differenttypes of plastic materials. However, it is believed that biopolymers maybe preferred. It is contemplated that polymers of lactic acid, lactidesl-lactides, and isomers of lactic acids and/or lactides may bepreferred. Of course, the suture 224 can also be formed of manydifferent types of plastic materials.

Although it is presently preferred to form the suture 224 and retainer222 of different materials, the suture and retainer could be formed ofthe same material if desired. By forming the suture 224 of a materialhaving a transition temperature range which is at least partially abovethe transition temperature range of the retainer 222, bonding of theretainer to the suture without significant deformation of the suture isfacilitated.

In the embodiment of the retainer 222 illustrated in FIG. 12 and 13, theplastic material of the retainer 222 is heated to a temperature in itstransition temperature range by applying heat to a portion of theretainer disposed between the two passages 232 and 234. This results ina central portion of the plastic material forming the retainer 222 beingheated into its transition temperature range while the outercircumference of the cylindrical retainer 222 is maintained at atemperature below the transition temperature range of the plasticmaterial of the retainer.

In the specific embodiment of the retainer 222 illustrated in FIGS. 12and 13, a generally conical recess 250 is formed in the central portionof the retainer 222. The recess 250 (FIG. 13) is spaced equal distancesfrom the passages 232 and 234 and has a central axis which is parallelto the central axes of the passages 232 and 234. The central axis of therecess 250 is coincident with a central axis of the cylindrical retainer222. In this specific embodiment of the invention, a heater element 254having a conical end portion 256 is used to heat the retainer 222. Ofcourse, other devices, such as a laser, could be used to heat theretainer 222.

After the portions 238 and 240 of the suture 224 have been inserted intothe openings or passages 232 and 234 and the suture and retainer movedto the desired positions relative to the body tissue 226 and 228, theheater element 254 is inserted into the recess 250. Heat is conductedfrom the heater element 224 to the plastic material in the centralportion of the retainer 222. The plastic material in the central portionof the retainer 222 is heated into its transition temperature range. Asthis occurs, the plastic material in the central portion of the retainer222 changes from a solid condition in which it has a fixed form to aviscous condition. The plastic material adjacent to the cylindricalouter side surface of the retainer is not heated into the transitiontemperature range and maintains its original configuration.

When the plastic material in the central portion of the retainer 222 hasbeen heated into the transition temperature range and has a viscouscondition, the material readily flows and molds itself around the outerside surface 242 (FIG. 15) of the suture 224. As this occurs, theconfiguration of the suture 224 remains unaltered and there is nosignificant deformation of the suture 224. The heating element 254 isthen removed from the recess 250 and the plastic material of theretainer 222 is cooled to a temperature below the transition temperatureof the material. As the plastic material of the retainer 222 is cooledto a temperature below its transition temperature, the plastic materialbonds to the suture 224 to provide a solid interconnection between theretainer and the suture.

In the embodiment of the invention illustrated in FIGS. 12-15, thesuture 224 is a monofilament suture. In the embodiment of the inventionillustrated in FIG. 16, the suture is a braided suture. Since theembodiment of the invention illustrated in FIG. 16 is generally similarto the embodiment of the invention illustrated in FIGS. 12-15, similarnumerals will be utilized to designate similar components, the suffixletter (a) being associated with the embodiment of the inventionillustrated in FIG. 16 to avoid confusion.

A retainer 222a formed of a plastic material is bonded to a suture 224aby heating the plastic material of the retainer 222a into its transitiontemperature range. After the plastic material of the retainer 222a hasflowed around the suture 224a while the plastic material of the sutureis at a temperature below the transition temperature range of theplastic material of the suture, the plastic material of the retainer iscooled to a temperature below the transition temperature range of theplastic material of the retainer. As the plastic material of theretainer 222a is cooled, a secure bond is obtained between the plasticmaterial of the retainer 222a and the suture 224a. This secure bond isobtained without significant deformation of the suture 224a.

In accordance with a feature of the embodiment of the inventionillustrated in FIG. 16, the suture 224a is a braided suture. Thus, thesuture 224a is formed by plurality of monofilament strands which areintertwined to form the braided suture 224a. When the plastic materialof the retainer 222a is heated to a temperature above its transitiontemperature, the plastic material of the retainer 222a flows between andaround the strands of the braided suture 224a. Upon cooling of theplastic material of the retainer 222a to a temperature below itstransition temperature, a secure bond is obtained between the materialof the retainer 222a and the strands of the braided suture 224a.

In the embodiment of the invention illustrated in FIG. 17, the polymerchains of the plastic material forming the retainer are orientedrelative to the suture. The orientation of the polymer chains of theretainer are such that the bonding which is obtained between the sutureand the retainer includes a mechanical interconnection due tocontracting of the polymer chains as the plastic material of theretainer is heated. Since the embodiment of the invention illustrated inFIG. 17 is generally similar to the embodiment of the inventionillustrated in FIGS. 12-15, similar numerals will be utilized todesignate similar components, the suffix letter "b" being associatedwith the numerals of FIG. 17 in order to avoid confusion.

The retainer 222b has a generally cylindrical configuration. The suture224b has portions which extend through the retainer 222b. Portions ofthe suture 224b are disposed in passages (not shown) corresponding tothe passages 232 and 234 of FIG. 12. The retainer 222b and suture 224bare formed of the same plastic materials as the retainer 222 and suture224 of FIGS. 12-15.

In accordance with a feature of the embodiment of the inventionillustrated in FIG. 17, the retainer 222b has polymer chains,illustrated schematically by lines 262, which are disposed in apredetermined orientation relative to the retainer 222b. In theillustrated embodiment of the invention, the polymer chains 262 areorientated with their longitudinal axes extending parallel to thecentral axis of the cylindrical retainer 222b and parallel to thelongitudinal axes of the portions of the suture 224b disposed withinpassages in the retainer.

Upon heating of the central portion of the retainer 222b, the polymerchains 262 of the plastic material in the central portion of theretainer 222b contract in an axial direction. Thus, the distance betweencircular end surfaces 264 and 266 of the retainer 222b decreases to agreater extent and the outside diameter of the retainer 222b. Thisresults in a mechanical gripping of the portions of the suture 224bdisposed within the retainer 222b by the plastic material of theretainer.

In the embodiments of the invention illustrated in FIGS. 12-17, portionsof the suture are disposed in cylindrical passages which extend throughthe retainer and have central axes which are parallel to a central axisof the retainer. In the embodiment of the invention illustrated in FIG.18, portions of the suture extend through retainer passages which areskewed relative to the central axis of the retainer. Since theembodiment of the invention illustrated in FIG. 18 is generally similarto the embodiments of the invention illustrated in FIGS. 12-17, similarnumerals will be utilized to designate similar components, the suffixletter "c" being associated with the numerals of FIG. 18 to avoidconfusion.

In the embodiment of the invention illustrated in FIG. 18, a cylindricalretainer 222c is formed of a plastic material. A pair of passages 232cand 234c are formed in the retainer 222c. A suture 224c, formed of aplastic material, has portions 238c and 240c which are received in thepassages or openings 232c and 234c. A central recess 250c is formed inthe retainer 222c to receive a heater element 254c when the plasticmaterial of the retainer 222c is to be heated. The retainer 222c andsuture 224c are formed of the same plastic materials as the retainer 222and suture 224 of FIGS. 12-15.

In accordance with a feature of the embodiment of the inventionillustrated in FIG. 18, the passages 232c and 234c have central axeswhich are skewed in an acute angle to the central axis of the retainer222c. Thus, the suture 224c is inserted into the passage 232c through acircular opening 272 in a circular end surface 266c of the retainer222c. The passage 232c has axially tapering side surface which forms aportion of a cone. The axially tapering configuration of the sidesurface of the passage 232c enables the side surface of the passage tosecurely grip the suture 224c at a location where an oval opening 274 isformed in the cylindrical outer side surface of the retainer 222c. Thelongitudinal central axis of the passage 232c is skewed at an acuteangle relative to the central axis of the cylindrical retainer 222c.

The portion 240c of the suture 224c is inserted into the passage 234c.The passage 234c has the same tapered configuration as the passage 232c.The longitudinal central axis of the passage 234c is skewed at an acuteangle to the central axis of the cylindrical retainer 222c. Thelongitudinal central axis of the passage 234c is also skewed at an acuteangle to the central axis of the passage 232c.

During use of the apparatus illustrated in FIG. 18, the suture 224c isplaced in a desired position relative to body tissue 226c and 228c. Theportions 238c and 240c are then inserted through the passages 232c and234c in the retainer 222c. The suture 224c the then tightened toposition the retainer 222c relative to the body tissue 226c and 228c.

Once this has been done, the material of the retainer 222c is heated byinserting a heater element 254c into the recess 250c in the centralportion of the retainer 222c. In this specific embodiment of theretainer 222c illustrated in FIG. 18, the polymer chains of the plasticmaterial forming the retainer 222c are oriented with their longitudinalaxes extending parallel to the longitudinal central axis of the retainer222c, in the same manner as illustrated schematically by the lines 262for the retainer 222b in FIG. 17. Therefore, upon heating of theretainer 222c, the polymer chains contract to grip the portions 232c and234c under the influence of forces extending transversely to thelongitudinal central axes of the portion 238c and 240c of the suture224c.

As the material in the central portion of the retainer 222c is heatedinto its transition temperature range, the material of the retainerflows around the portions 238c and 240c of the suture 224c disposed inthe passages 232c and 234c. The temperature of the material forming theretainer 222c is maintained at a temperature which is below thetransition temperature for the plastic material of the suture 224c.Therefore, the plastic material of the retainer 222c flows around theplastic material of the suture 224c without significant deformation ofthe suture.

A secure bonding of the plastic material of the retainer 222c to theplastic material of the suture 224c is obtained by cooling the materialof the retainer to a temperature below its transition temperature. Thissecure bonding is obtained without significant deformation of the suture224c so that the suture maintains its strength and is capable of holdingthe body tissue 226c and 228c in a desired manner.

From the foregoing, it is apparent that the apparatus and methods of theembodiments of the invention illustrated in FIGS. 12-18 may be used insuturing body tissue. A portion 238 of a suture 224 is inserted into anopening in a retainer 222 formed of a plastic material. At least aportion of the retainer 222 is heated to a temperature in a transitiontemperature range of the plastic material forming the retainer. Thesuture 224 is maintained at a temperature below the transitiontemperature range of a plastic material forming the suture while theretainer 222 is heated. The plastic material of the retainer 222 flowsaround the plastic material of the suture 224. A bonding of the plasticmaterial of the retainer 222 to the plastic material of the suture 224is effected by cooling the plastic material of the retainer to atemperature below its transition temperature range. The foregoing stepsare performed without significant deformation of the plastic material ofthe suture 224. It should be understood that the plastic materials ofthe sutures and retainers of the embodiments of the inventionillustrated in FIG. 16-18 are interconnected in the same manner as theembodiment of FIGS. 12-15.

From the above description of the invention, those skilled in the artwill perceive improvements, changes and modifications. Suchimprovements, changes and modifications within the skill of the art areintended to be covered by the appended claims.

The following is claimed:
 1. A method of suturing body tissue, saidmethod comprising the steps of placing a suture formed of a plasticmaterial relative to the body tissue, inserting a portion of the sutureinto an opening in a retainer formed of a plastic material, heating atleast a portion of the retainer to a temperature in a transitiontemperature range of the plastic material forming the retainer whilemaintaining the plastic material of the suture at a temperature belowthe transition temperature range of the plastic material forming thesuture, flowing the plastic material of the retainer around the plasticmaterial of the suture while the plastic material of the suture is at atemperature below the transition temperature range of the plasticmaterial of the suture, and, thereafter, bonding the plastic material ofthe retainer to the plastic material of the suture by cooling theplastic material of the retainer to a temperature below the transitiontemperature range of the plastic material of the retainer.
 2. A methodas set forth in claim 1 wherein said step of inserting a portion of thesuture into an opening in a retainer includes inserting a first portionof the suture into a first opening in the retainer, said method furtherincluding the step of inserting a second portion of the suture into asecond opening in the retainer, said step of heating at least a portionof the retainer includes heating a portion of the retainer disposedbetween the first and second openings.
 3. A method as set forth in claim1 wherein said step of heating at least a portion of the retainer to atemperature in the transition temperature range of the plastic materialforming the retainer includes heating a portion of the retainer spacedfrom a peripheral edge portion of the retainer to a temperature in thetransition temperature range of the plastic material of the retainerwhile maintaining the peripheral edge portion of the retainer at atemperature below the transition temperature range of the plasticmaterial of the retainer.
 4. A method as set forth in claim 1 whereinsaid step inserting a portion of the suture into an opening in theretainer includes inserting the suture into a retainer having polymerchains oriented in a direction extending along a longitudinal axis ofthe portion of the suture received in the opening in the retainer, saidstep of heating at least a portion of the retainer includes contractingthe polymer chains to contract the plastic material of the retainer andgrip the suture with the retainer.
 5. A method as set forth in claim 1wherein at least a portion of the transition temperature range of theplastic material forming the suture is higher than the transitiontemperature range of the plastic material forming the retainer, saidstep of heating at least a portion of the retainer to a temperature inthe transition temperature range of the plastic material of the retainerincludes heating at least a portion of the retainer to a temperaturewhich is below the transition temperature range of the plastic materialof the suture.
 6. A method as set forth in claim 1 further includingmaintaining the configuration of an outer side surface of a portion ofthe suture disposed in the opening in the retainer constant duringflowing of the plastic material of the retainer around the plasticmaterial of the suture.
 7. A method as set forth in claim 1 wherein saidsteps of flowing the plastic material of the retainer around the plasticmaterial of the suture and bonding the plastic material of the retainerto the plastic material of the suture are performed without significantdeformation of the plastic material of the suture.
 8. A method as setforth in claim 1 wherein said step of placing a suture formed of aplastic material relative to body tissue includes placing a sutureformed by a plurality of strands of plastic material relative to bodytissue, said step of flowing the plastic material of the retainer aroundthe plastic material of the suture includes flowing the plastic materialof the retainer around and between the strands of the suture.
 9. Amethod as set forth in claim 1 wherein said step of placing a sutureformed of a plastic material relative to body tissue includes placing asuture having a transformation temperature range which is above 190°Celsius, said step of heating at least a portion of the retainer to atemperature in the transition temperature range of the plastic materialof the retainer includes heating the portion of the retainer to atemperature which is below 190° Celsius.
 10. A method of suturing bodytissue, said method comprising the steps of placing a suture formed of aplastic material relative to the body tissue, inserting a portion of thesuture into an opening in a retainer formed of a plastic material,heating at least a portion of the retainer, and, thereafter, bonding theplastic material of the retainer to the plastic material of the suture,said steps of heating at least a portion of the retainer and bonding theplastic material of the retainer to the plastic material of the suturebeing performed without significant deformation of the plastic materialof the suture.
 11. A method as set forth in claim 10 wherein an outerside surface area on a portion of the suture inserted into the openingin the retainer has a first configuration prior to and after performanceof said steps of heating at least a portion of the retainer and bondingthe plastic material of the retainer to the plastic material of thesuture.
 12. A method as set forth in claim 10 further including the stepof flowing the plastic material of the retainer around the plasticmaterial of the suture after heating at least a portion of the retainer.13. A method as set forth in claim 10 wherein said step of inserting aportion of the suture into an opening in a retainer includes inserting afirst portion of the suture into a first opening in the retainer, saidmethod further including the step of inserting a second portion of thesuture into a second opening in the retainer, said step of heating atleast a portion of the retainer includes heating a portion of theretainer disposed between the first and second openings.
 14. A method ofsuturing body tissue, said method comprising the steps of placing asuture formed of a plastic material relative to the body tissue,inserting a first portion of the suture into a first opening in aretainer formed of a plastic material, inserting a second portion of asuture into a second opening in the retainer, thereafter, heating aportion of the retainer disposed between the first and second openingsin the retainer, and bonding the plastic material of the retainer to thesuture.
 15. A method as set forth in claim 14 wherein said step ofheating a portion of the retainer disposed between the first and secondopenings in the retainer includes moving a heating element into a recessformed in the retainer at a location between the first and secondopenings in the retainer.
 16. A method of suturing body tissue, saidmethod comprising the steps of placing a suture relative to body tissue,inserting a portion of the suture into an opening in a retainer formedof a plastic material, heating a portion of the plastic material of theretainer, flowing the heated plastic material of the retainer around anouter side surface of the suture without flowing the material of thesuture, and bonding the plastic material of the retainer to the suture.17. A method as set forth in claim 16 further including the step ofinserting a portion of the suture into a second opening in the retainer,said step of heating a portion of the plastic material of the retainerincludes heating the plastic material of the retainer at a locationbetween the openings in the retainer.
 18. A method as set forth in claim16 wherein said steps of heating a portion of the plastic material ofthe retainer, flowing the heated plastic material of the retainer aroundan outer side surface of the suture and bonding the plastic material ofthe retainer to the suture are performed without significant deformationof the plastic material of the suture.
 19. A method as set forth inclaim 16 wherein said step of heating a portion of the plastic materialof the retainer includes heating at least a portion of the plasticmaterial of the retainer to a temperature in a transition temperaturerange of the plastic material, said step of flowing the heated plasticmaterial of the retainer being performed while at least a portion of theplastic material of the retainer is in the transition temperature range.20. A method as set forth in claim 16 wherein said step of heating atleast a portion of the retainer includes contracting polymer chains ofthe plastic material of the retainer to contract the plastic material ofthe retainer and grip the suture with the retainer.